Safety valves



Apr-i121, 1964 c. D. P. SMALLFYPEICEI SAFETY VALVES Filed 001;. 51, 1960 United States Patent land Filed Oct. 31, 1960, Ser. No. 66,172 Claims priority, application Great Britain Mar. 22, 1960 6 Claims. (Cl. 181-37) The invention relates to a valve which is adapted to open when a predetermined fluid pressure is reached and is adapted primarily for use as a safety valve in the exhaust line from a pneumatically-operated system. The object of the invention is a valve of the kind referred to which is of simple construction and will remain open after aflording pressure relief.

According to the invention a valve which is adapted to open when a predetermined fluid pressure is reached, and to remain open, includes a hollow cylindrical body provided with an inlet for the fluid and having, in its cylindrical wall, at least one outlet normally sealed by a contractile member which engages round the exterior of the cylindrical wall, the contractile member being supported such that it will be displaced axially of the said wall by the escape of the fluid under a pressure superior to the predetermined one, whereby afterwards to leave the outlet unsealed.

According to a still further feature a plurality of the outlets are arranged on a circle round the body for coaction with a single contractile member.

The contractile member is a band of a resilientlyextensible, impervious material which is engaged round the body in a condition of tension so as to cover the outlet or outlets, the tension in the band being chosen to set the predetermined pressure, within the body, at which a said outlet Will be opened with resultant displacement of the band axially of the body to an unsealing position.

According to a still further feature the valve can have a body of a porous material and form a silencer for a gas exhaust, the outlet or outlets being adapted to open when a predetermined back-pressure arises in the body due to the pores of the latter becoming choked.

In the accompanying drawings:

FIGURE 1 is a longitudinal section through one form of valve in accordance with the invention adapted for use as a silencer for a pneumatic exhaust;

FIGURE 2 is a section on the line 2--2 of FIGURE 1, and

FIGURE 3 is a sectional diagram illustrating the operation of the valve.

Referring to FIGURES 1 and 2 the valve includes a porous cylindrical element having a closed end 11, and its opposite end open and made sealingly fast with an adaptor 12 provided with a screw thread 13 for enabling it to be connected to an exhaust pipe from a pneumatic system. The element is provided in its cylindrical wall with a plurality of ports 14 which are arranged in a ring and are normally covered by a contractile band 15 of a natural or synthetic rubber or of another suitable, resiliently-extensible, impervious material.

The band is arranged to be under tension so that should the pressure within the element rise above that which is predetermined by the pressure of the band, the latter will be forced away from the ports to allow the excess pressure to escape. By the nature of the band the escaping pressure passing round its opposite edges will tilt the band laterally and force it to one side as indicated in FIGURE 3 whereby to leave the ports open so that the valve will not close again should the pressure within the "ice element afterwards drop. Thus, as soon as choking of the pores of the element 10 with suspended matter from the exhaust from the pneumatic system impairs its permeability the pressure within the element will rise and cause one or more of the ports to open for relieving the excess pressure. This results in the band 15 being moved axially of the element to an out-of-the-way position, and the escaping of the fluid from the ports will give a warning that the filter element ought to be removed for cleaning, or renewed.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A valve, adapted to open when a predetermined fluid pressure is reached, comprising a cylindrical body provided with an inlet for the fluid, said body having at least one outlet port in its cylindrical wall, and a circumferentially contractile member engaged around the exterior of said cylindrical wall and positioned over said outlet port to seal said outlet port, said contractile member free to move axially on said cylindrical body, so that said contractile member is adapted to be displaced axially of said body by fluid escaping from said outlet port whereby afterwards to leave the latter at least partially uncovered.

2. A valve, adapted to open when a predetermined fluid pressure is reached, comprising a cylindrical body provided with an inlet for the fluid, said body having a plurality of outlet ports in its cylindrical wall, said outlet ports circumferentially spaced and arranged with their axes in a single radial plane of said body, and a circumferentially contractile member engaged around the exterior of said cylindrical wall and positioned over said outlet ports to seal said outlet ports, said contractile member free to move axially on said cylindrical body, so that said contractile member is adapted to be displaced axially of said body by fluid escaping from said outlet ports whereby afterwards to leave at least one of the latter at least partially uncovered.

3. A valve, adapted to open when a predetermined fluid pressure is reached, comprising a cylindrical body provided with an inlet for the fluid, said body having at least one outlet port in its cylindrical wall, and a circumferentially contractile band of a resiliently-extensible material which is impervious to the fluid and is engaged around said body and positioned over said outlet port in a condition of tension to seal said outlet port, the tension in the band setting the fluid pressure within said body at said band will be displaced to unseal said port, and said contractile band free to move axially on said cylindrical body so that said band is adapted to be displaced axially of said body by fluid escaping from said outlet port whereby afterwards to leave it at least partially uncovered.

4. A silencer for a gas exhaust comprising a cylindrical porous body provided with an inlet for the gas, said body pervious to the gas, said body having at least one outlet port in its cylindrical wall, and a circumferentially contractile member engaged around the exterior of said cylindrical wall and positioned over said outlet port to seal said outlet port, the contractile effort of said contractile member adapted to be overcome when matter suspended in said gas clogs the pores of said porous body to an extent which will cause the gas pressure within said body to rise to a value at which it will act through said port to displace said contractile member out of its sealing position, and said contractile member free to move axially on said cylindrical body so that said contractile member is adapted to be displaced axially of said body by fluid escaping from said outlet port whereby afterwards to leave it at least partially uncovered.

5. A silencer for a gas exhaust comprising a cylindrical porous body having one end open, an impervious tubular adaptor, said body having its open end sealingly engaged with said adaptor whereby the latter provides an inlet for gas to enter said body, said body pervious to the gas, said body having a plurality of outlet ports in its cylindrical wall, said outlet ports circumferentially spaced and arranged with their axes in a single radial plane of said body, and a circumferentially contractile member engaged around the exterior of said cylindrical wall and positioned over said outlet ports to seal said outlet ports, the contractile effort of said contractile member adapted to be overcome when matter suspended in said gas clogs the pores of said porous body to an extent which will cause the gas pressure within said body to rise to a value at which it will act through said port to displace said contractile member out of its sealing position, and said contractile member free to move axially on said cylindrical body so that said contractile member is adapted to be displaced axially of said body by fluid escaping from said outlet ports whereby afterwards to leave them at least partially uncovered.

6. A silencer for a gas exhaust, according to claim 5, in which the circumferentially contractile member is a band of resiliently-extensible material which is impervious to the fluid and is engaged around the body in a condition of tension, the tension in the band setting the gas pressure within said body at which said band will be displaced to unseal said ports.

References Cited in the file of this patent UNITED STATES PATENTS 

4. A SILENCER FOR A GAS EXHAUST COMPRISING A CYLINDRICAL POROUS BODY PROVIDED WITH AN INLET FOR THE GAS, SAID BODY PERVIOUS TO THE GAS, SAID BODY HAVING AT LEAST ONE OUTLET PORT IN ITS CYLINDRICAL WALL, AND A CIRCUMFERENTIALLY CONTRACTILE MEMBER ENGAGED AROUND THE EXTERIOR OF SAID CYLINDRICAL WALL AND POSITIONED OVER SAID OUTLET PORT TO SEAL SAID OUTLET PORT, THE CONTRACTILE EFFORT OF SAID CONTRACTILE MEMBER ADAPTED TO BE OVERCOME WHEN MATTER SUSPENDED IN SAID GAS CLOGS THE PORES OF SAID POROUS BODY TO AN EXTENT WHICH WILL CAUSE THE GAS PRESSURE WITHIN SAID BODY TO RISE TO A VALUE AT WHICH IT WILL ACT THROUGH SAID PORT TO DISPLACE SAID CONTRACTILE MEMBER OUT OF ITS SEALING POSITION, AND SAID CONTRACTILE MEMBER FREE TO MOVE AXIALLY ON SAID CYLINDRICAL BODY SO THAT SAID CONTRACTILE MEMBER IS ADAPTED TO BE DISPLACED AXIALLY OF SAID BODY BY FLUID ESCAPING FROM SAID OUTLET PORT WHEREBY AFTERWARDS TO LEAVE IT AT LEAST PARTIALLY UNCOVERED. 